Magnetic random access memory (MRAM) is a type of non-volatile random-access memory. An MRAM usually includes a magnetic tunnel junction (MTJ) structure including two magnetic layers separated by a thin tunnel insulating layer. The resistance of the MTJ structure depends on whether the magnetization directions in the two magnetic layers are the same or opposite to each other. Thus, the MTJ structure can switch between a low-resistance state and a high-resistance state depending on magnetization directions. The two different resistance states can be used to represent “0” and “1”, respectively
MRAM has a performance similar to that of static random-access memory (SRAM), a density similar to that of dynamic random-access memory (DRAM), but lower power consumption than DRAM. MRAM is faster and suffers no degradation over time in comparison to flash memory. Therefore, MRAM is considered a good candidate for replacing SRAM, DRAM, and flash memory.
An MRAM usually uses in-plane magnetic anisotropy (IMA) materials in the magnetic layers of the MTJ structure. In such an MTJ structure, the magnetization directions in the magnetic layers are parallel to a surface of the magnetic layers. When the device size is reduced, it may be difficult to achieve both a low write current and a thermal stability in an in-plane MTJ structure.